Semiconductor device including plateless package

Abstract

A semiconductor device including a metallurgically compatible unplated package is provided. The package includes a plateless copper alloy die mount area to which a semiconductor die is attached. The semiconductor die is metallized on its mounting surface to provide electrical contact. A metallic solder which is compatible with both the copper alloy and the die metallization joins the die to the die mount area. The package further includes a plateless copper alloy lead portion which is physically joined to the die mount area. The top surface of the semiconductor die is provided with a patterned metallization making electrical contact to selected portions of the die. Electrical contact is made between the top surface die metallization and the lead portion of the package by ultrasonically bonded copper ribbon. The die and interconnecting ribbon is then enclosed by an epoxy encapsulant or by a welded metal cover.

We claim: 
     
       1. A semiconductor device comprising in combination: an unplated copper alloy die mount package portion; a semiconductor die having first and second surfaces; a first metallization on said first surface and making electrical contact thereto; a non lead-based, non gold-based metallic solder metallurgically compatible with said first metallization and with said copper alloy die mount package portion, said solder joining said die to said die mount package portion; a second metallization patterned on said second surface and making electrical contact to selected portions thereof; a copper alloy lead connector package portion mechanically fixed with respect to said die mount package portion; copper connecting means ultrasonically bonded between and electrically interconnecting said second patterned metallization and said lead connector package portion; and means for enclosing said semiconductor die, said copper connecting means, and a portion of each of said die mount and lead connector package portions. 
     
     
       2. The device of claim 1 further comprising a polyimide die coat applied over said semiconductor die and said copper connecting means. 
     
     
       3. The device of claim 2 wherein said means for enclosing comprises a molded plastic housing. 
     
     
       4. The device of claim 1 wherein said copper alloy die mount package portion comprises a bonding pedestal secured to a metallic base. 
     
     
       5. The device of claim 4 wherein said copper alloy lead connector package portion comprises posts insulatively secured in openings through said metallic base. 
     
     
       6. The device of claim 5 wherein said means for enclosing comprises a metallic cover bonded to said metallic base. 
     
     
       7. The device of claim 1 wherein said copper connecting means comprises copper ribbon. 
     
     
       8. The device of claim 1 wherein said first metallization comprises sequential layers of titanium, nickel and silver. 
     
     
       9. The device of claim 1 wherein said second metallization comprises sequential layers of titanium, nickel and copper. 
     
     
       10. The device of claim 1 wherein said metallurgically compatible solder comprises tin, silver and antimony. 
     
     
       11. A semiconductor device comprising: a semiconductor die having first and second surfaces; an unplated copper alloy package die mount portion; an unplated copper alloy package lead portion; a first multi-layer metallization making contact to said first surface of said die and including a surface layer of silver; a metallic solder joining said silver and said die mount portion and metallurgically compatible with each; a second multi-layer metallization contacting said second surface of said die and including a surface layer of copper; copper connecting means ultrasonically bonded between said copper and said lead portion; and means for encapsulating said semiconductor die.